Working memory (WM), which underlies the temporary storage and manipulation of information, is critical for multiple aspects of cognition and everyday life. Nevertheless, research examining WM specifically in older adults remains limited, despite the global rapid increase in human life expectancy. We examined WM in a large sample (N=754) of healthy older adults (aged 58-89) in a non-Western population (Chinese speakers) in Taiwan, on a digit n-back task. We tested the influence not only of age itself and of load (1-back vs. 2-back), but also effects of both sex and education, which have been shown to modulate WM abilities. Mixed-effects regression revealed that, within older adulthood, age negatively impacted WM abilities (with linear, not nonlinear, effects), as did load (worse performance at 2-back). In contrast, education level was positively associated with WM. Moreover, both age and education interacted with sex. With increasing age, males showed a steeper WM decline than females; with increasing education, females showed greater WM gains than males. Together with other findings, the evidence suggests that age, sex, and education all impact WM in older adults, but interact in particular ways. The results have both basic research and translational implications, and are consistent with particular benefits from increased education for women.
Although there is little dispute about the impact of the US opioid epidemic on recent mortality, there is less consensus about whether trends reflect increasing despair among American adults. The issue is complicated by the absence of established scales or definitions of despair as well as a paucity of studies examining changes in psychological health, especially well-being, since the 1990s. We contribute evidence using two cross-sectional waves of the Midlife in the United States (MIDUS) study to assess changes in measures of psychological distress and well-being. These measures capture negative emotions such as sadness, hopelessness, and worthlessness, and positive emotions such as happiness, fulfillment, and life satisfaction. Most of the measures reveal increasing distress and decreasing well-being across the age span for those of low relative socioeconomic position, in contrast to little decline or modest improvement for persons of high relative position.
We evaluate the variability in estimates of self-reported physical limitations by age across four nationally representative surveys in the US. We consider its implications for determining whether, as previous literature suggests, the US estimates reveal limitations at an earlier age than in three countries with similar life expectancy: England, Taiwan, and Costa Rica. Based on cross-sectional data from seven population-based surveys, we use local mean smoothing to plot self-reported limitations by age for each of four physical tasks for each survey, stratified by sex. We find substantial variation in the estimates in the US across four nationally-representative surveys. For example, one US survey suggests that American women experience a walking limitation 15 years earlier than their Costa Rican counterparts, while another US survey implies that Americans have a 4-year advantage. Differences in mode of survey may account for higher prevalence of limitations in the one survey that used a self-administered mail-in questionnaire than in the other surveys that used in-person or telephone interviews. Yet, even among US surveys that used the same mode, there is still so much variability in estimates that we cannot conclude whether Americans have better or worse function than their counterparts in the other countries. Seemingly minor differences in question wording and response categories may account for the remaining inconsistency. If minor differences in question wording can result in such extensive variation in the estimates within a given population, then lack of comparability is likely to be an even greater problem when examining results across countries that do not share the same language or culture. Despite the potential utility of self-reported physical function within a survey sample, our findings imply that absolute estimates of population-level prevalence of self-reported physical limitations are unlikely to be strictly comparable across countries—or even across surveys within the same population.
The increased risk for poor physical and mental health outcomes for older parents in Mexico who have an adult child living in the United States may contribute to an increased risk for cognitive impairment in this population. The objective of this study was to examine if older adults in Mexico who have one or more adult children living in the United States are more or less likely to develop cognitive impairment over an 11-year period compared to older adults who do not have any adult children living in the United States.
The hypothesis that the S allele of the 5-HTTLPR serotonin transporter promoter region is associated with increased risk of depression, but only in individuals exposed to stressful situations, has generated much interest, research and controversy since first proposed in 2003. Multiple meta-analyses combining results from heterogeneous analyses have not settled the issue. To determine the magnitude of the interaction and the conditions under which it might be observed, we performed new analyses on 31 data sets containing 38 802 European ancestry subjects genotyped for 5-HTTLPR and assessed for depression and childhood maltreatment or other stressful life events, and meta-analysed the results. Analyses targeted two stressors (narrow, broad) and two depression outcomes (current, lifetime). All groups that published on this topic prior to the initiation of our study and met the assessment and sample size criteria were invited to participate. Additional groups, identified by consortium members or self-identified in response to our protocol (published prior to the start of analysis) with qualifying unpublished data, were also invited to participate. A uniform data analysis script implementing the protocol was executed by each of the consortium members. Our findings do not support the interaction hypothesis. We found no subgroups or variable definitions for which an interaction between stress and 5-HTTLPR genotype was statistically significant. In contrast, our findings for the main effects of life stressors (strong risk factor) and 5-HTTLPR genotype (no impact on risk) are strikingly consistent across our contributing studies, the original study reporting the interaction and subsequent meta-analyses. Our conclusion is that if an interaction exists in which the S allele of 5-HTTLPR increases risk of depression only in stressed individuals, then it is not broadly generalisable, but must be of modest effect size and only observable in limited situations.
We compare physical performance from three U.S. national surveys and nationally representative surveys in England, Taiwan, and Costa Rica. Method: For each performance test, we use local mean smoothing to plot the age profiles by sex and survey wave and then fit a linear regression model to the pooled data, separately by sex, to test for significant differences across surveys controlling for age and height. Results: Age profiles of performance vary across U.S. surveys, but levels of lung function (peak expiratory flow) and handgrip strength in the United States are as high as they are in the other three countries. Americans also perform as well on the chair stand test as the English and Costa Ricans, if not better, but exhibit slower gait speed than the English at most ages. Discussion: With the exception of walking speed, we find little evidence that older Americans have worse physical performance than their peers.
Using five waves of the Taiwanese Longitudinal Study of Aging (1996–2011), we investigate (1) the association between family members’ education and the age trajectories of individuals’ depressive symptoms and (2) gender differences in those relationships. Our examination is guided by several theoretical frameworks, including social capital, social control, age as leveler, and resource substitution. Nested models show that having a more educated father is associated with lower depressive symptoms, but the relationship disappears after controlling for respondent’s education. Including spouse’s education attenuates the coefficient for respondent’s education. A similar pattern appears when children’s education is added to the model. Among all the family members, children’s education has the strongest association with depressive symptoms, with a similar magnitude for both genders, although its strength gradually weakens as respondents age. Our findings suggest the importance of the transfer of resources from children to parents and how it may affect mental health at older ages.
We consider a broad set of variables used by social scientists and clinicians to identify the leading predictors of five‐year survival among American adults. We address a question not considered in earlier research: Do the strongest predictors of survival vary by age, sex or race/ethnicity? The analysis uses hazard models with 30 well‐established predictors to examine five‐year survival in the National Health and Nutrition Examination Survey. We find that the simple measure of self‐assessed health and self‐reported measures of functional ability and disability are the strongest predictors in all demographic groups, and are generally ranked considerably higher than biomarkers. Among the biomarkers, serum albumin is highly ranked in most demographic groups, whereas clinical measures of cardiovascular and metabolic function are consistently among the weakest predictors. Despite these similarities, there is substantial variation in the leading predictors across demographic groups, most notably by race and ethnicity
Social inequalities in health and disability are often attributed to differences in childhood adversity, access to care, health behavior, residential environments, stress, and the psychosocial aspects of work environments. Yet, disadvantaged people are also more likely to hold jobs requiring heavy physical labor, repetitive movement, ergonomic strain, and safety hazards. We investigate the role of physical work conditions in contributing to social inequality in mobility among older adults in Mexico, using data from the Mexican Health and Aging Survey (MHAS) and an innovative statistical modeling approach. We use data on categories of primary adult occupation to serve as proxies for jobs with more or less demanding physical work requirements. Our results show that more physically demanding jobs are associated with mobility limitations at older ages, even when we control for age and sex. Inclusion of job categories attenuates the effects of education and wealth on mobility limitations, suggesting that physical work conditions account for at least part of the socioeconomic differentials in mobility limitations in Mexico.
Researchers often rely on respondents' self-rated health (SRH) to measure social disparities in health, but recent studies suggest that systematically different reporting styles across groups can yield misleading conclusions about disparities in SRH. In this study, we test whether this finding extends to ethnic differences in self-assessments of health in particular domains. We document differences between US-born whites and four Latino subgroups in respondents' assessments of health in six health domains using data from the second wave of the Los Angeles Family and Neighborhood Survey (N = 1468). We use both conventional methods and an approach that uses vignettes to adjust for differential reporting styles.
The Social Environment and Biomarkers of Aging Study (SEBAS) is a nationally representative longitudinal survey of Taiwanese middle-aged and older adults. It adds the collection of biomarkers and performance assessments to the Taiwan Longitudinal Study of Aging (TLSA), a nationally representative study of adults aged 60 and over, including the institutionalized population. The TLSA began in 1989, with follow-ups approximately every 3 years; younger refresher cohorts were added in 1996 and 2003. The first wave of SEBAS, based on a sub-sample of respondents from the 1999 TLSA, was conducted in 2000. A total of 1023 respondents completed both a face-to-face home interview and, several weeks later, a hospital-based physical examination. In addition to a 12-h (7 pm–7 am) urine specimen collected the night before and a fasting blood specimen collected during the examination, trained staff measured blood pressure, height, weight and waist and hip circumferences. A second wave of SEBAS was conducted in 2006 using a similar protocol to SEBAS 2000, but with the addition of performance assessments conducted by the interviewers at the end of the home interview. Both waves of SEBAS also included measures of health status (physical, emotional, cognitive), health behaviours, social relationships and exposure to stressors. The SEBAS data, which are publicly available at [ http://www.icpsr.umich.edu/icpsrweb/NACDA/studies/3792/version/5 ], allow researchers to explore the relationships among life challenges, the social environment and health and to examine the antecedents, correlates and consequences of change in biological measures and health.
This study examines whether frailty is associated with mortality independently of physiological dysregulation (PD) and, if so, which is the more accurate predictor of survival. Data come from the Social Environment and Biomarkers of Aging Study. We use Cox proportional hazard models to test the associations between PD, frailty, and 4- to 5-year survival. We use Harrell’s concordance index to compare predictive accuracy of the models. Both PD and frailty are significantly, positively, and independently correlated with mortality: Worse PD scores and being frail are associated with a higher risk of dying. The overall PD score is a more accurate predictor of survival than frailty, although model prediction improves when both measures are included. PD and frailty independently predict mortality, suggesting that the two measures may be capturing different aspects of the same construct and that both may be important for identifying individuals at risk for adverse health outcomes
Persons of Mexican origin and some other Latino groups in the United States have experienced a survival advantage compared with their non-Latino White counterparts, a pattern known as the Latino, Hispanic, or epidemiological paradox. However, high rates of obesity and diabetes among Latinos relative to Whites and continued increases in the prevalence of these conditions suggest that this advantage may soon disappear. Other phenomena, including high rates of disability in the older Latino population compared with Whites, new evidence of health declines shortly after migration to the United States, increasing environmental stressors for immigrants, and high-risk values of inflammatory markers among Latinos compared with Whites support this prediction. One powerful counterargument, however, is substantially lower smoking-attributable mortality among Latinos. Still, it is questionable as to whether smoking behavior can counteract the many forces at play that may impede Latinos from experiencing future improvements in longevity on a par with Whites.
Telomere length has generated substantial interest as a potential predictor of aging-related diseases and mortality. Some studies have reported significant associations, but few have tested its ability to discriminate between decedents and survivors compared with a broad range of well-established predictors that include both biomarkers and commonly collected self-reported data. Our aim here was to quantify the prognostic value of leukocyte telomere length relative to age, sex, and 19 other variables for predicting five-year mortality among older persons in three countries. We used data from nationally representative surveys in Costa Rica (N = 923, aged 61+), Taiwan (N = 976, aged 54+), and the U.S. (N = 2672, aged 60+). Our study used a prospective cohort design with all-cause mortality during five years post-exam as the outcome. We fit Cox hazards models separately by country, and assessed the discriminatory ability of each predictor. Age was, by far, the single best predictor of all-cause mortality, whereas leukocyte telomere length was only somewhat better than random chance in terms of discriminating between decedents and survivors. After adjustment for age and sex, telomere length ranked between 15th and 17th (out of 20), and its incremental contribution was small; nine self-reported variables (e.g., mobility, global self-assessed health status, limitations with activities of daily living, smoking status), a cognitive assessment, and three biological markers (C-reactive protein, serum creatinine, and glycosylated hemoglobin) were more powerful predictors of mortality in all three countries. Results were similar for cause-specific models (i.e., mortality from cardiovascular disease, cancer, and all other causes combined). Leukocyte telomere length had a statistically discernible, but weak, association with mortality, but it did not predict survival as well as age or many other self-reported variables. Although telomere length may eventually help scientists understand aging, more powerful and more easily obtained tools are available for predicting survival.
There are large socioeconomic disparities in adult mortality in Russia, although the biological mechanisms are not well understood. With data from the study of Stress, Aging, and Health in Russia (SAHR), we use Gompertz hazard models to assess the relationship between educational attainment and mortality among older adults in Moscow and to evaluate biomarkers associated with inflammation, neuroendocrine function, heart rate variability, and clinical cardiovascular and metabolic risk as potential mediators of that relationship. We do this by assessing the extent to which the addition of biomarker variables into hazard models of mortality attenuates the association between educational attainment and mortality. We find that an additional year of education is associated with about 5% lower risk of age-specific all-cause and cardiovascular mortality. Inflammation biomarkers are best able to account for this relationship, explaining 25% of the education-all-cause mortality association, and 35% of the education-cardiovascular mortality association. Clinical markers perform next best, accounting for 13% and 23% of the relationship between education and all-cause and cardiovascular mortality, respectively. Although heart rate biomarkers are strongly associated with subsequent mortality, they explain very little of the education-mortality link. Neuroendocrine biomarkers fail to account for any portion of the link. These findings suggest that inflammation may be important for understanding mortality disparities by socioeconomic status.
Despite myriad efforts among social scientists, epidemiologists, and clinicians to identify variables with strong linkages to mortality, few researchers have evaluated statistically the relative strength of a comprehensive set of predictors of survival. Here, we determine the strongest predictors of five-year mortality in four national, prospective studies of older adults. We analyze nationally representative surveys of older adults in four countries with similar levels of life expectancy: England (n = 6113, ages 52+), the US (n = 2023, ages 50+), Costa Rica (n = 2694, ages 60+), and Taiwan (n = 1032, ages 53+). Each survey includes a broad set of demographic, social, health, and biological variables that have been shown previously to predict mortality. We rank 57 predictors, 25 of which are available in all four countries, net of age and sex. We use the area under the receiver operating characteristic curve and assess robustness with additional discrimination measures. We demonstrate consistent findings across four countries with different cultural traditions, levels of economic development, and epidemiological transitions. Self-reported measures of instrumental activities of daily living limitations, mobility limitations, and overall self-assessed health are among the top predictors in all four samples. C-reactive protein, additional inflammatory markers, homocysteine, serum albumin, three performance assessments (gait speed, grip strength, and chair stands), and exercise frequency also discriminate well between decedents and survivors when these measures are available. We identify several promising candidates that could improve mortality prediction for both population-based and clinical populations. Better prognostic tools are likely to provide researchers with new insights into the behavioral and biological pathways that underlie social stratification in health and may allow physicians to have more informed discussions with patients about end-of-life treatment and priorities.
Models of stress incorporate both the environmental demands experienced by individuals (stressors) and the appraisal of these life events (perceptions). Because little is known about the extent to which experience and perceptions are related, we examine this relationship in a nationally representative population of older Taiwanese adults.
Using growth models applied to data from 3 waves (1999, 2003, and 2007) of the Taiwan Longitudinal Study of Aging, we (a) investigate patterns of change in perceived stress in later adulthood and (b) examine how experienced stressors influence perceived stress. Participants were asked to report the presence of, and in some cases the degree of, exposure to stressors including total number of medical conditions, difficulty with activities of daily living, difficulty with mobility functions, being financially worse off compared with the prior wave, experiencing the death of a child, and experiencing a marital disruption. Items reflecting perceived stress included concerns about various domains pertaining to the respondent and his/her family member.
Our results indicate that exposure to stressors increases, whereas perceived stress decreases, over time. Change in exposure to stressors is not generally associated with change in perceptions of stress, with the exception of a summary measure of health-related exposure to stressors. An increase in poor health over time is related to an increase in perceived stress in all domains.